The median for group 2 is almost double the median for group 1. Group 2's median would be 80, and 1's would be a little over 40, which is about half. The median is the middle line of the box on the graph.
Oxygen's valence, based on the Number of valence electrons or outermost electrons that oxygen has would be 6.
Saprophytes are fungi that are capable of getting nourishment from decaying plants in order to live their lives longer. They are known to stay in rich soil and in various dead trees. They often reside in decaying wood as well.